Which of the following noble gases has the maximum positive electron gain enthalpy?

Options

A. `Xe`
B. `He`
C. `Kr`
D. `Ne`

Explanation

To determine which noble gas has the maximum positive electron gain enthalpy, we need to analyze the properties of noble gases and their electron gain enthalpy values. Here’s a step-by-step solution:

### Step 1: Understand Electron Gain Enthalpy
Electron gain enthalpy is the amount of energy released or absorbed when an electron is added to a neutral atom in the gas phase. For noble gases, this value is typically positive because they are already stable with a complete valence shell.

### Step 2: Identify the Noble Gases
The noble gases are:
- Helium (He)
- Neon (Ne)
- Argon (Ar)
- Krypton (Kr)
- Xenon (Xe)
- Radon (Rn)

### Step 3: Analyze Electron Gain Enthalpy Trends
Noble gases generally have a positive electron gain enthalpy because they do not readily accept electrons due to their stable electronic configuration. However, there is a trend in the values of electron gain enthalpy among these gases:
- The electron gain enthalpy becomes less positive (or more negative) as we move down the group from helium to radon.

### Step 4: Compare the Electron Gain Enthalpy Values
The values of electron gain enthalpy for noble gases are approximately:
- Helium: +0.0 kJ/mol (very low)
- Neon: +116 kJ/mol (highest among noble gases)
- Argon: +48 kJ/mol
- Krypton: +34 kJ/mol
- Xenon: +12 kJ/mol
- Radon: +- 2 kJ/mol (very low)

### Step 5: Conclusion
Among the noble gases, Neon has the highest positive electron gain enthalpy, making it the correct answer.

### Final Answer
The noble gas with the maximum positive electron gain enthalpy is **Neon (Ne)**.

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